Hey Mr. Green! Sport-utility vehicles have better gas mileage these days than they used to. How do they compare with other cars in their miles-per-gallon ratings? 

—Fred in Los Angeles, California

SUVs are getting somewhat more competitive when it comes to fuel economy, with 15 of the latest models now exceeding 30 miles per gallon. But SUVs still generally burn more fuel and are not as efficient as other cars. You're better off buying a smaller car, as various models now get 40 miles per gallon or more. 

I applaud you for asking the question in the first place. While we enviros fret over fuel consumption and efficiency, one academic study from 2013 revealed that for most consumers, fuel cost is the 11th most important concern when choosing which car to buy—behind seating comfort—while only 5 percent of Americans would pay a premium for environmentally friendly features. Judging by TV ads, you get the impression that automakers themselves aren't too concerned about miles per gallon; they continue to push pickups, SUVs, and cars with big engines while ignoring gas mileage. Meanwhile, vehicles are now the number one source of CO2 in the United States, having surpassed power plants and factories in 2017. According to the latest data, emissions from new vehicles sold last year were 5 percent higher than back in 2013.